Core drill and bit



April 1, 1930.v w. l. McLAuGHLlN CORE .DRILL AND BIT Filed July 28. 1926 2 Sheets-Shet 1 FIE. 1

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Y E N T08 Mms/Mv April 1, 1930. l w. l. MCLAUGHLIN. 1,752,388

' CORE DRILL AND BIT Filed July 28, `192e; 2 sheets-sheet 2 FIIE E Patented Apr'.L 1,`

- fiJNITEp STATES PATENT ori-*Ica mun I. ICLAUGNHLIN, F SAN FRANCISCO, CALIFORNIA, 'ASSIGNOR '1'0 STANDARD I OIL COMPANY lOfl CALIFORNIA, OF SAN FRANCISCO, CALIFORNIA, .A CORPORATION conn nimm nu: Brr

animating mea my ze;

This invention relates generally to drills of the rotary type which are adapted to remove a core `from the strata being drilled.

Rotary core, drillscommonly comprise a '5 core retainer rotatably mounted within a core barrel, thebarrel having a suitable bit at its lower end t cutaway the formation about -a central core which is permitted to progress upwardly into the retainer. Lubricating mud is generall circulated ldownthrough the drill stem an discharged adjacent the bit to carr awa the cuttings and reduce friction. ithvt eordinary t peof bit the core is frequentlyfractured or urned during the process' of drilling or is washedawa b the lubricating mud, thus making it of ou ful or useless Avalue for determining the condi-- tion of the sub-strata. I have found that this fracturing and burning of the core is caused by excessive friction betweez. thebit and the formation being drilled due to faulty lubrication, and to inadequate .facilities for carry- -ingaway the borings, with the result'that the teeth become clogged with mud. This fracturing also frequently results from friction due to relatively large surfaces in contact between the bit and the core, to the absence of positive means for centering thebit and t0 the entrance vof lborings into the core retainerl It is an object of this invention to devise a` core bit in which all tendency to fracture or to burn the core will be minimized.

It is a further obsct of this invention to devise a core bit w 'ch will bei adequately lubricated to reduce friction and effectively remove all borings.

Itis a further object of t 's invention lto construct a core bit in such a' manner as to' preill'entdeposits of mud forming upon the It is a further object ofr thisinvention-to devise a core bit which will be selfcentering i to prevent side lsway and resulting fractur.. i ofthecore.'

t isl a lfurther object of this invention-to prevent.. washing' aws of theA vcore byl `.the ubricating mu .whl 'is being circulated through the drill.

1c is naher object of invention t at.

ieee. serrure. 125s'za. i

vise a core bit of relatively simple construction which ma be attached to any standard core barrel an which will cut rapidly in soft formations. v

It is another object of this invention to `devise a core drillA incorporating aspartic'ular t pe of bit which will prevent entry of cuttlngs into the core retainer. v Further objects of the invention will apn pear from the following description in which I have set forth the preferred embodiment of my invention. It is to be understood that the scope of the invention vis to be determined from the appended claims and the state of the' prior art. 5

Referring to the drawingszf.

Figure 1 1s a side elevational view showing a bit constructed in accordance with this invention. v

Fig. 2 is a bottom view showing the arrangement of the teeth upon the bit.

' F1g. 3 is a cross section taken along the line i 3-3 of Fig. 2 showing the bit attached to a suitable .form of core barrel.

Aes

cured to a suitable form of core barrel, pref-` .erably of the type lhaving an innerrotatable core retainer... Lubricating mud is circulated downwardly through the core barrel and discharged through passageways provided in the body of the bit, these passageways being arranged so as to dischar e the mud directly vfrom the lower face of t e bit. The cutting teeth depend from the 'lower face of the bit. lfnd a'e spaced regularly about the axis of the arre v Thus as shown'in the drawings (Fig. 3)

the bit has been indicated generally at 10 vand has been shown as secured' to the lower end of a hollow core .barrel 11,"the barrel being secured'at its upper end to a suitable pipe string 'or drill stem;l Within the core barrelll there has been shown a core retainer 12 of suitable construction which is adapted to receive a core vformed by the bit 10. The bit itself comprises a body member 13 which may be provided with a suitable threaded extension Vor sleeve 14 for attachment "t6-itl? lowerendof the core barrel 11." 'order loo' 1 to ass the core thiou `h the retainer 12 the bo y member is provi edwith a central bore 16 having a minimum diameter which is substantially less than the internal diameter of the core retainer. l

substantially in the form of' two intersecting conical surfaces having a `common axis, the outer conical surface having a substantially greater slope ratio than the inner. De-

I section between the beveled surfaces 17 and r`18. In Ysomel instances a single passageway pending from the lower face of the bit are a plurality of teeth 19 which are regularly spaced about the central bore 16. The par- 'ticular form of teeth shown are commonly known as the fish tail type, two diametrically opposite teeth forming the two fins for one tail. Thus the rear side of each tooth is shown as beveled as at 20 to form a cutting edge 21, this-'cutting edge being ad-l vanced in the direction o rotation beyond the forward side of the tooth. In order to secure more eliicient cutting action and to direct cuttings away from the central bore 16, these cutting edges are preferably inclined rearwardly from the direction of rotation with respect to the radius of the bit as indicated in Fig. 2. Thus the advancing face of each tooth is at an angle to the direction Iof rotation in order to exert a shearing action upon the formation being cut. As a means for centeringvthe bit, and in order to prevent side sway the cutting edges are -not extended to lie within a plane surface but are sloped downwardly away from) the cen- `tral bore so that the core will be formed with .,a conical base.

The lubricatin mud is preferably introduced directly a ong the lower face of the bit andvthus there has been provided a plu- Ifrality of passageways which communicate at their upper ends with the space between the core retainer 12 and the barrel 11, and at their lower ends communicate directly with the lower face of the bit' adjacent the interbetwee two successive teeth is sutlicient although it is preferable to provide two passageways on eitherside of each tooth as shown in Fig. 2. With this arrangement the lubri- 'eating mud is directed Aagainst the sides of the teeth, thus washingaway and preventin 'the accumulation of mud deposits. In

or er to minimizefriction between the sidesof the -bit and/the core barrel and theA walls of the formation being cut, the teeth are preferably provided with extensions 26 which proJect upwardly above the beveled surface 18 and thus cause the bit to act as a reamer to establish the maximum diameter of the hole being drilled. This arrangement also` and the bit. The particular form of retainerl shown is split longitudinally to provide'two halves 27 yto which are secured at their lower ends a ring 28. -The central bore 16 is enlarged as at 29 snugly to 'receive the lower end of this retainer, thus forming a shoulder 25 adjacent the lower end of 'the-bit. The

friction between the retainer and bit. Spring fingers 32 may also be. provided within the retainer for centering and marking. the core. The central bore 16 and thus the shoulder -25 is preferably ilared upwardly as shown in Fig. 3 in order to reduce-'the amount of ring 28 may be rovided with centering dogs 30 and with a earing 31 for reducing the` surface which is in frictional'contact with c the core being formed.

When the devlce 1s in operation lubricating mud introduced into the pipe 'string' is circulated downwarg'ly between the core retainer and barrel a y lower face of the bit throuh the passageways 23. The mud as it is ischarged washes `against the sides of the teeth, thus carrying away borings as quickly as the are formed.

and preventing mud deposits. he combined discharged from the effect of having the cutting edges inclined rearwardly from the radius of the bit'in the directionof -rotation, and the upwardly sloped lower faceof the bit, serves to mim v mize entr of the cuttings into the core retainer an therefore the core is permitted to progress upwardly into the retainer without danger of clogging. Because of the proximity between the mner ends of the cutting edges and the lower end of the central bore 16, the vcirculating mud will not tendto )wash against the face of the `core to cause it to be worn away. The fact thatthe cuttin edges are also inclined downwardly from t tral bore, serves to form a strong conical base for the core,` thus minimizing the tendenc of the core to break at its baseand also ten s to center the bit upon the formation being cut, thus preventing side swa The lubrication may be` malntained adequate at all times to keep the bit relatively cool, thus reducing 'friction and preventing burning of 'the core. The extensions 26,serve to ream A my hand.

out the hold and also to agitate the cuttings and thus assist in prevent-ing cloggingof t e bit.

I claim: 1. A rotary-more bit comprising a body member having a central bore, the lower face ofthe member having annular surfaces bevy eled upwardly away from the bore on two distinct angles to form a face corresponding f 1o generally to a pair of concentric intersecting cones forming a circular shoulder along their line of intersection.

2. A rotary core bit comprising a body member having a central bore, the lower end of, said member 'having annular surfaces beveled on two distinct angles to form a face corresponding 'generally to a pair of concentric intersecting cones forming a circular shoulder along their line of intersection, the lower '20 face sloped `upwardly away from. the bore, and a plurality of teeth disposed u on said face, said teeth extending along bot bevelsof said face and beyond the outer periphery of the body. 3. A rotary core bit comprising a body member having a central bore, the lowerend of said body member having annular surfaces beveled on two distinct angles to form a face corresponding generally to a pair of concentric' intersecting cones forming a circular lshoulder along their line of intersection, the

. Flower face sloped upwardly away from the bore, and a pluralityl of teeth disposed upon said face, said teet extending along both beveled surfaces of said face and beyond the outer peripher of the body, said teeth also having edges oped downwardly away from saidbore.

l 4. A rotary core bit comprising a body 40 member having a central bore to receive a core, a plurality of teeth depending from the lower face of said member, the lower face of said member being beveled u wardly away from the vbore on at least two distinct angles 45,. and forming'a face. corresponding generally to a pair of concentric intersecting cones forming a circular shoulder along their line.

of intersection, and assa es for fluid com'- municating with sai beve ed face.

5. A rotary 'core bit comprising a body member having a. central bore to receive a core, a luralityy of teeth depending from the lower said member being beveled u wardly away -55 from the bore on at least two distinct angles Aand forming a face corresponding generally to a pair of concentric Vintersecting cones forming a circular shoulder along their line of intersection, 3 municating with the lower beveled face between said teeth. 4 L; InA testimony whereof, I have hereunto set WILLIAM I, MeLAUGHL'IN.

ace of said member, the lower face of and passagesfor fluid comportion of said 

